Applied Mechanics and Materials Vol. 899

Abstract: Structural dynamics in structural engineering analysis involves the modal parameters (natural frequency, mode shape and damping ratio). The modal parameters of engineering structures is mainly influenced by the damping and stiffness properties. This research paper presents the reliability of CELAS element in the finite element modelling to represent the stiffness parameter. The simplified engineering structure considered in this study is a mass-spring system with multi-degree of freedom. Experimental modal testing is performed using an electro-magnetic vibration shaker as an exciter and an accelerometer to record the natural frequency of the system. HyperMesh normal mode analysis is used to compute the natural frequency of the mass-spring system. The comparative evaluation is performed in order to identify the accuracy of the natural frequencies obtained from the modelling analysis and the measured counterparts. Consequently, it is found that the element CELAS has a good capability to represent as the stiffness parameter in the finite element modelling.

Abstract: Power generation from fossil fuels in the recent years causes pollution to the environment, thus renewable energy must be considered as an alternative. Solar energy comes directly from the sun and harnessing this energy is crucial for a sustainable future. In this research, a parabolic solar dish collector was utilized to harness the solar energy. The parabolic dish was hybridized with a thermoelectric generator (TEG) to produce both heat and electricity simultaneously. Since TEG has no moving parts, it requires almost no maintenance, thus making it reliable and robust. This paper presents the experimental investigation performed on the concentrator to convert heat energy from the concentrated solar power using TEGs. The goal of the project was to efficiently generate electricity by using the concentrating dish to concentrate the solar radiation onto the TEG. The TEG was installed on the focal point of the concentrating dish to convert the thermal energy into electricity directly. Air-cooled, fan-cooled and water-cooled cooling method were introduced to cool the generators. At the end of the experiment, it was found out that water-cooled cooling method induced the highest voltage among the other cooling methods.

Abstract: Air core is an important parameter in pressure swirl atomizer since formation of air core determines the thickness of the discharged liquid sheet and the effective flow area of nozzle discharge. This consequently will affect the coefficient of discharge and the spray angle. This study conducted for the investigation of the relation between dimensionless numbers on the air core diameter. Dimensionless numbers are helpful aid for the quantification of independent parameters involving atomizer design and operating conditions simultaneously. Reynolds number, Re and orifice-to-swirl chamber diameter ratio, N are the dimensionless numbers selected for this study. Despite of the availability of study on the effect of dimensionless numbers on air core diameter, more study requires especially for smaller N. An experimental test-rig was constructed to conduct the performance test of the atomizer. Acquired images were analyzed using image-processing software. It was found that N has more significant effect on the change of air core diameter compared to Re. However, it is observed that at Re = 40000, N = 0.07 produces almost similar air core diameter with N = 0.25 at Re < 20000. In contrast, with N = 0.5, air core diameter produces are larger even at Re < 20000. Hence, it can be concluded that both Re and N are important parameters in characterizing the air core diameter in pressure-swirl atomizer.

Abstract: This paper presents the development of a ladder climbing robot prototype. The development of the prototype includes constructing the basic software and hardware for the robot. The robot controller is designed using Arduino Mega 2560 software implemented in Arduino IDE with C programming. The hardware development involves constructing the main chassis and climbing arm with servomotor, DC geared motor and motor driver. An algorithm to climb ladder is developed with application of Infrared (IR) sensor and ultrasonic sensors. Significantly, the robot prototype is tested on ladders of different rung spacing. In the future, a base with wheels will be constructed for the robot to carry load and move on ground with obstacle avoidance capability and side grippers will be constructed to improve climbing performance of the robot on vertical ladder; this project will contribute to future research on similar topics.

Abstract: Bio-inspiration is a design method where natural observation was used to solve a mechanical problem. In this study, a bio-inspiration meth-od was used to design a flapping wing for a Micro Air Vehicle (MAV) that is inspired by bat wings. The objective of this study is to study the aerodynamic performance of a flapping wing based on bat wings at different angles of attack. This is done using Computational Fluid Dynamics (CFD) simulation where the aerodynamic performance a wing derived from a natural bat wing shape was studied. The wing was generated by tracing the wing shape of a bat wing and the shape was generalized to produce the wing shape. In the simulation, a 2-way Fluid Structure Interaction (FSI) method was used where a Finite Element Analysis (FEA) solver was coupled with a CFD solver to simulate the wing during flapping flight. The flight condition was set at 1 m/s flight speed at a flapping frequency of 2.5Hz. From the results, it was shown that the wing has a zero-lift angle at 0^o and a stall angle at 16^o. It is also shown that the wing has a minimum drag angle at 3^o and a maximum aerodynamic efficiency at angle of attack 12^o.

Abstract: Polypropylene bags are widely used in many industries especially in agriculture and food industry. However, industries especially in food or fertilizer industries, need to use the polypropylene bags that can withstand a high level of humidity. To overcome this problem, a two-layers bag is required. This two-layers bag consists of outer layer woven bag and inner layer polypropylene bag. Currently they are produced by using conventional method where they are assembled manually by the workers. This manual method causes longer production time process, a high number of workers, and higher cost for mass production. To enhance the operation performance, automated polypropylene bags assembly system is proposed. By using an automated system, it can improve quality and consistency of processes, and reduced direct human labor costs and expenses where the worker is unneeded for assembling the polypropylene bag. To overcome this problem, this project is dedicated to design and develop a new Automated Polypropylene Bag Assembly Machine (APBAM) to operate the process automatically. This machine will execute three main processes - Grasping, Handling and Feeding. This paper will focus on the design of pneumatic actuator for grasping polypropylene bags in upward and downward motion. The design will be calibrated, analyzed and evaluated. The design of automated polypropylene bags assembly system will help to solve some of the problems that have been identified.

Abstract: In this paper, an examination hall assistive robot (EHAR) had been developed to operate in an examination hall, to collect and deliver extra answer booklet for examination candidates. The systems will respond to user or student request through a table transmitter on each table via radio communication. The request by the students is collected by a CPU, before it is transmitted to the robot. The robot moves by following line on floor and read RFID tag for localization purpose. The robot has the ability to stop or avoid obstacle along the path received from the information obtained by the ultrasonic sensors. After the integration process, the performance of the developed system had been tested. The test had been carried out by moving EHAR through 3 points (RFID tags), where EHAR is required to turn on certain angle and direction after each tags read. The test was then repeated for another 10 times to obtained correct average results. The percentages of the average successful turns made by the EHAR are 83.3%. Therefore, it is hoped that this system will be implemented in exam halls and serves its purposes.

Abstract: This paper focuses on the characterized of the mechanical properties and hyper elastic behavior of lab made skin. Bovine Serum Albumin (BSA) combined with gelatin as a base. BSA is a plasma lead concentrations or heparin plasma which is separated from blood sample and it is not associated with significant changes in iron or hemoglobin concentrations. In general, the gelatin is widely used as the best material for skin substitution since it exhibits the characteristic of human skin. However, the lab made skin layer was made of non-halal type gelatin (Type B). The methodology process started by adding the BSA and using the type A gelatin to carry out the mechanical properties and hy-per elastic behavior of halal lab made skin layer. A uniaxial tensile test standard that being used in this study is ASTM D412. The raw data (Load-Extension) from computational was plotted on graph stress-strain. The numerical approach such as Mooney-Rivlin model and Yeoh’s model were selected to analyze a stress-stretch of composition gelatin and BSA. From the results Mooney-Rivlin model, the con-stant, C1 is in the range of (0.0187-0.0658) MPa and C2 is in the range of (0.0628-0.0737) MPa. Meanwhile the constant, CP for Yeoh model is in the range of (0.0748-0.0861) MPa. As a conclusion, the composition of gelatin and Bovine Serum Albumin is a best combina-tion as it increases the strength of the lab made skin layer. Therefore, the most suitable composition is 10 wt.% of gelatin and Bovine Serum Albumin.

Abstract: This research was conducted to provide a feasible method for reconstructing the 3D model of mandibular bone to undergo finite element analysis to investigate von Mises stress, deformation and shear stress located at the cortical bone, cancellous one and neck implant of the proposed dental implant design. Dental implant has become a significant remedial approach but although the success rate is high, the fixture failure may happen when there are insufficient host tissues to initiate and sustain the osseointegration. Computerised Tomography scan was conducted to generate head images for bone reconstruction process. MIMICS software and 3-matic software were used to develop the 3D mandibular model. The reconstructed mandibular model was then assembled with five different 3D models of dental implants. Feasible boundary conditions and material properties were assigned to the developed muscle areas and joints. The highest performance design with the best responses was the design B with the value for the von Mises stress for the neck implant, cortical and cancellous bone were 7.53 MPa, 16.91 MPa and 1.34 MPa respectively. The values for the maximum of micromotion for the neck implant, cortical and cancellous bone of design B were 20.60 μm, 21.17 μm and 5.83 μm respectively. Shear stress for neck implant, cortical and cancellous bone for this design were 0.15 MPa, 4.74 MPa and 1.54 MPa respectively. The design with a cone shaped hole which is design B was the proper design when compared with other designs in terms of von Misses stress, deformations and shear stress.